Rare and little-known ammonites from the Lower and Middle Jurassic of the Western and Central Balkan Mts (Bulgaria)

This paper presents insufficiently or previously unknown Jurassic ammonites from 21 localities and sections of the Western and Central Balkan Mts (Bulgaria). The total stratigraphical range of the studied fauna corresponds to a broad interval, from the Pliensbachian (Lower Jurassic) to the Callovian (Middle Jurassic), with emphasis on the ammonites from the Bajocian–Callovian interval. These ammonites belong to 36 species and 23 genera that are affiliated to 12 ammonite families: Polymorphitidae, Acanthopleuroceratidae, Amaltheidae, Hildoceratidae, Graphoceratidae, Strigoceratidae, Sonniniidae, Stephanoceratidae, Oppeliidae, Tulitidae, Parkinsoniidae, and Perisphinctidae. Of them, 13 species have been left in open nomenclature. This account comprises both newly recorded ammonite taxa and redefined ammonite species from older collections. The new evidence also includes the upper Bathonian species Siemiradzkia mangoldi sp. n., which was recorded from south-eastern France as well. Although being represented mainly by single specimens, often with no other supporting material, the newly discovered taxa have high stratigraphical significance, being both valuable additions to well-known Bulgarian ammonite zonal associations and new indications of ammonite successions that have quite poorly been identified in Bulgaria to date. In this regard, they are useful for better dating of the sedimentary successions in Bulgaria and are valuable for the purposes of correlation outside Bulgaria.